Many organic materials, such as polymers, fuels, and lubricants, are normally susceptible to oxidative deterioration and tend to suffer severe degradation and/or discoloration during processing and/or later use unless they are stabilized.
The compounds which have previously been proposed for use in stabilizing these materials have frequently been phenolic compounds, and some such compounds have been very successfully employed as antioxidants for some of the normally oxidizable materials. However, no single compound could be the best possible antioxidant for each of the variety of organic materials which are normally susceptible to oxidative deterioration, since:
(1) the compounds which have the lowest volatility and highest thermal stability are not necessarily those which have the most suitable melting points, the least tendency to degrade to highly-colored compounds, and the greatest ability to stabilize organic materials during processing, PA1 (2) some of the organic materials (e.g., the polymers) are less capable than others (e.g., fuels and lubricants) of tolerating the substantial discoloration that occurs when many phenolic compounds are subjected to processing conditions, PA1 (3) some antioxidant compounds are so volatile and have such poor thermal stability that they are unsuitable for use in organic materials for which high processing temperatures and/or long-term stabilization are required, and PA1 (4) some antioxidant compounds have melting points so high as to present a drawback to their use in materials which must be processed at low or moderate temperatures.
Thus, it is necessary to have different antioxidants to serve the different needs of the various organic materials which require stabilization.
Because of the need for these different antioxidants for different organic materials, it would be desirable to be able to find a class of antioxidants which could be derived from a common intermediate or a common genus of intermediates that could be easily modified so as to provide the different antioxidant properties required in the variety of specific market needs.
As disclosed in U.S. Pat. Nos. 3,780,103 (Knell), 3,808,273 (Burdet et al.), 3,927,091 (Huber-Emden et al.), 3,996,194 (Gencarelli et al.), 4,098,760 (Cornell), 4,100,191 (Fischer et al.), and 4,132,702 (Schmidt et al.) and Netherlands Patent Application 7905000 (Cincinnati Milacron Chemicals), it is known that some amides containing substituted hydroxyphenyl groups have been found to be useful as stabilizers for some organic materials which are normally susceptible to oxidative deterioration.
N,N-bis(3,5-di-t-butyl-4-hydroxybenzyl)acetamide is disclosed by G. A. Nikiforov et al. in Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2765-2770, 1989.